Circuit breaker with electrode disposed between two arc interrupting devices



Aug. 2, 1955 E. SALZER 2,7M,645

CIRCUIT BREAKER WITH ELECTRODE DISPOSED BETWEEN TWO ARC INTERRUPTING DEVICES Filed March 15 1951 5 Sheets-Sheet l & 2

Aug. 2, 1955 E, s z R 2,714-,645

CIRCUIT BREAKER WITH ELECTRODE DISPOSED BETWEEN TWO ARC INTERRUFTING DEVICES l95l 3 Sheets-Sheet 2 Filed March xx\x\\\\\ Aug. 2, 1955 E. sALzER 1 5 CIRCUIT BREAKER WITH ELECTRODE DISPOSEID BETWEEN TWO ARC INTERRUPTING DEVICES Filed March 15, 1951 3 Sheets-Sheet 3 (u, M 5/3. w 4.

CIRCUIT BREAKER WTH ELECTRODE DISPOSED BETWEEN TW@ ARC INTERRUPTING DEVICES Application March 15, 1951, Serial No. 215,723 19 Clains. (Ci. 200-150) This invention relates to electric circuit breakers and more particularly to high speed oil circuit breakers of the fluid blast type.

In circuit breakers of the above type the arc is formed in an arc enclosing device and extinguished therein by a blast of gas resulting froni the decomposition by the arc of the oil within the arc enclosing device. The pressure required for producing the arc extinguishing gas blast is generated in whole or in part by the heat of the arc. Since arc extinction is predicated upon the amount of gas and pressure generated by the arc, the arc extinguishing action of such devices is relatively high if the current under interruption is relatively high but decreases with decreasing current strength. There is a critical low current range Wherein the amount of gas and the pressure generated by the arc tend to be insufficient for extinguishing the arc as rapidly as desired for limiting the length of the arc, the arcng time and the arc energy. A limited improvement of these unfavorabie conditions has been obtained, heretofore, by shunting the arc by a resistor. This results in a rapid extinction of the resistor shunted arc and series insertion of the resistor into the circuit under interruption. As the extent of separation between the Contacts of the circuit breaker is increased, a second arc is forrned in series with the resistor. The series resistor limits the current in the second arc and increases the transient power factor during the entire interrupting process. Final interruption of the circuit takes place when the second arc in series with the resistor is being extinguished.

Heretofore tank type oil circuit breakers have been used comprising a stack structure forrned of superposed liquid absorbent plates which are submerged in the arc extinguishing Iiquid and provided with a substantially straight contact passageway. Such stack structures have been associated With resistors both for limiting overvoltages tending to be generated on interruption of capacitive or small inductive currents and for equalizing the voltage distribution where series arrangements of breaks involving a plurality of such stack structures are being used. in these prior art circuit breakers difficulties were frequently encountered, however, in rapidly interrupting the resistor limited arc current.

In accordance with the invention claimed a new and improved oil circuit breaker is provided which embodies a stack type interrupting device of increased effectiveness and interrupting etliciency. This new circuit breaker subdivides the stack type interrupting devices into two portions, i. e., one portion for efiecting rapid extinction of the resistor shunted section of the arc and another portion for eTecting rapid extinction of the arc formed in series with the resistor.

It is, therefore, one object of the present invention to provide a new and improved arc interrupting device which effectively interrupts resistor limited arc currents.

Another object of this invention is to provide a new and improved arc extnguishing device in which relatively tates Patent Ofice 2314545 Patented Aug. 2, 1955 low current arcs formed in series With a resistor are confined to generate high gas nterrupting pressures.

A further object of this invention is to provide an improved arc extingushing device in which an auxiliary electrode used for inserting a resistor into the circuit under rate locations.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accornpanying drawing, in which:

Fig. 1 illustrates diagrammatically a circuit under interruption prior to extinction of the resistor shunted arc;

Fg. 2 llustrates diagrammatically the same circuit after extincton of the resistor shunted arc and prior to extinction Pig. 3 is an aXial cross sectional View of an arc extinguishing device embodying the present invention;

Fig. 4 is an axial cross sectional View of another arc extinguishing device embodying the present invention;

Fig. 5 is an axial cross sectional View of still another arc extinguishing device enibodying the present invention;

Fig. 6 is a side elevation of a pair of arc extinguishing devices mounted within a tank and illustrating the location of the resistor structures; and

Fig. 7 is a plan View of the circuit breaker structure illustrated in Fig. 6.

Referring more particularly to the d'awings by characters of reference, Figs. l and 2 diagrammatically illustrate an electric circuit 10 energized by an alternating current generator 11 and controlled by a circuit breaker 12. The electric circuit 1@ may have an inductance of a few henries and a capacitance of a few millifarads. The inductance may be represented by an inductive device 13, and the capacitance by a capacitor 14. Circuit breaker 12 comprises a tulip type stationary contact 15, a cooperating movable rod type contact 16, an auxiliary electrode 17, and a resistor Auxiliary electrode 17 is in the form of a sliding contact which transfers current to the movable contact 16. The resistance of resistor 18 is so chosen that it precludes the rise of switching voltages beyond a predetermined safe value.

As long as the circuit breaker 12 is closed, Contacts 15 and 16 are in engagement and resistor 18 is short circuited by movable rod contact 16. An arc is initiated between contacts 15 and 16 upon separaton thereof. The resistance of that arc increases with its length and reaches peak values approximately at the time of each natural current zero subsequent to arc initiation. The ratio of the currents through the arc and through the resistor 18 depends upon their relative resistance. Arc extinction occurs when the arc resistance exceeds the resistance of the resistor 18 to such an extent that almost the entire current flows through the resistor. Upon extinction of the arc formed between Contacts 15 and 16 the resistor 18 limits the current which flows through the circuit breaker 12. As shown in Fig. 2, a second arc is intiated between contact 16 and auxiliary electrode 17 upon separation thereof. The resistance of that arc increases with increasing separation between contact 16 and electrode 17 and after a current zero following separation of contact 16 and electrode 17 no arc reignition takes place. Final interruption of the circuit is then achieved.

If desirable there may be a small gap between contact 16 and the electrode 17 in place of the sliding ena however, the current under interruption is small, e. g., if a relatively long transmission line is being dropped on which there is no load, the pressure generated in chamber 32 by the capacitive line current may be insufiicient to extinguish the arc and the arc may repeatedly reignite or restrike.

Since the gap between probe electrode 43 and movable contact 27 is very small, the voltage drop along the arc formed between contacts 27 and 24 will soon exceed the breakdown voltage of the gap between probe electrode 43 and contact 27, resulting in a breakdown of that gap and shunting of the arc by the resistor 49. A resistor shunted arc is unstable and since that unstable arc is subjected to continued elongation and other action tending to increase the arc resistance and the arc voltage, the resistor shunted arc will soon be extinguished. This may occur shortly prior or shortly after the tip of contact 27 moves past probe electrode 43.

A resistor current arc is subsequently drawn between probe electrode 43 and movable contact 27. That arc is not merely drawn into oil filled space but is elongated within the lower portion of stack structure 33 which is particularly adapted for the extinction of low current arcs. To this end the cross sectional area of the helical passageways 35 at the lower ends thereof is greatly decreased and any lateral venting means are omitted from that portion of passageways 34, 35, extending through structure 21 thus tending to create the greatest possible pressure at this point of the stack structure.

At this point of the stack structure the amount of oil soaked material arranged close to the arc path is higher than anywhere else in the stack, and this tends likewise to increase the effectiveness of the lowest stack portion 21 relative to the extinction of small currents. The length of the stack structure situated below probe electrode 43 is sufiicient to interrupt any small resistor limited current therein, and to preclude any reignition or restrike after the movable contact 27 has been drawn out of member 39.

After the movable contact 27 has been moved past probe electrode 43, oil remaining in the helical passageways 35 above probe electrode 43 flows into the aXial passageway 34 and over probe electrode 43, thus tending to cool probe electrode 43 and to establish an insulating barrier between probe electrode 43 and movable contact 27.

While the shunt resistor 49 shown in Fig. 3 preferably has a linear resistance, a nonlinear shunt resistor may be used, if so desired.

The resistance value of the shunt resistor depends upon the part it is designed to play in interrupting the electric circuit. Critical clamping of the recovery voltage is obtained by using shunt resistance lower than where L is the lumped impedance and C the lumped capacitance of the circuit under interruption.

The effectiveness of the lower stack portion which interrupts the resistor current is of particular importance with regard to high speed reclosing duty because prolonged arc duration delays deionzation of the arc path at the point of the fault and thus prevents operation with short reclosing times.

Where the main purpose of the shunt resistor consists in limiting the overvoltage due to the presence of inductance L in the circuit under interruption, the resistor may be calculated to comply with any requirement imposed as to overvoltage limitation. The magnetic energy available in the circuit at the time of the interruption thereof may be expressed by the term /2L' This energy is converted into dielectric energy and determines the overvoltage incident upon interruption of the circuit. The exact magnitude of that overvoltage depends upon how the above structure 19 shown in Fig.

Conversion is effected, i. e., at what rate resistance, including arc resistance, is inserted into the circuit under interruption.

The main purpose of the shunt resistor may be the interruption of capacitive circuits or capacitance switching. This function of the shunt resistor involves aspects different from those which were considered above. The lower the shunt resistor, the more complete the discharge of the capacitance during the arcing time, the smaller the tendency of restriking after arc extinction. The capacitance to be discharged may be, for instance, a charged transmission line. If the capacitance has not been sufliciently discharged during the arcing time of the arc formed between Contacts 27 and 24, the restriking voltage across contact 27 and probe electrode 43 will be limited by the series resistor 49 and the circuit may be so heavily damped that build up of excessive overvoltages in the circuit will be efi'ectively precluded.

The lower the shunt resistance 49, the higher the current which must be interrupted along the stack portion 20 Situated below probe electrode 43. Since the magnitude of the arc current which must be interrupted along that stack portion is determined by the value of the shunt resistor 49, the interrupting duty of this stack portion is determined by the choice of the most suitable shunt reupon it. For instance, if the choice of a relatively low shunt resistance is conducive to relatively high shunt resistor currents, the lowest portion of the stack structure may readily be adapted to interruption of relatively ele- Vated resistor currents. If, on the other hand, the shunt resistance is relatively high, resulting in relatively small resistor currents, the portion of the stack structure situated below proble electrode 43 may be adapted to be best suited to that single purpose.

Fig. 4 shows an embodiment of the invention in an arc extinguishing structure 60 which has a smaller voltage and interrupting capacity rating than the arc extinguishng 3. Arc extinguishing structure 60 comprises a casting 61 adapted to be Secured to a bushing (not shown). A tulip type contact 62 provided with arc resisting inlays 63 is arranged within casting 61. The individual contact sectors of which contact 62 iS made up are connected by shunts 64 to casting 61.

A stack structure 65 is arranged within an insulating shell 66, and the latter is supported on casting 61 by means of an annular casting 67, ring 68 and screws 69. A pressure generating chamber 70 is formed between tulip contact 62 and the upper end of stack structure 65. A movable rod contact '71 arranged to cooperate with contact 62 is adapted to be moved within and through a central passageway 72 in stack structure 65. The arc extinguishing stack structure 65 is subdivided by an anis introduced into, and withdrawn from, the stack structure 65 through the orifice 74.

The upper portion of the stack structure serves to extinguish resistor shunted arcs drawn between contacts 71 and 62, and the lower portion of the stack structure 65 serves to extinguish arcs formed between contact 71 and electrode 73, which is in series with a resistor 75. nector element 76 in the shape of a screw threaded stud extends through a transverse bore 77 in shell 66 and serves to connect auxiliary electrode 73 into the circuit under interruption. The auxiliary electrode 73 shown in Fig. 4 includes one or more substantially U-shaped bronze through the slotted 79 spring ends. enter into holes 80 provided 7 rranged in coaxal relation with respect to both shell 66 and electrode 73.

The stack portion above auxiliary electrode 73 and the stack portion below auxiliary electrode 73 define substantially helical passageways 84 which communicate with the axial contact passageway 72 but do not communicate directly with each other. There will be a tendency to establish a substantially helical oil flow in both stacl portions Situated above and below auxiliary electrode 73. The central aperture 85 in auxiliary electrode 73 does not form part of the helical passageways above and below auxiliary electrode 73, but the whirling motion imparted to the oil within the space above electrode 73 continues at the level of that electrode and within the space defined by the central aperture 85 and cools effectively the arc terminal formed on electrode '73 or on any' U-shaped contact spring 7 8 thereof.

The circuit interrupting device shown in Fig. 5 embodying the invention claimed is characterized by the combination of two features, of which one consists in that an uxiliary electrode is 'arranged between the two axially outer ends' of an arc extirguishing stack structure 91 and the other consists in that a pressure generating charnber 92 is formed adjacent the end of the stack structure 91 remote from the point of arc initiation between a stationary tulip type contact 93 and a cooperating movable rod confact 94.

The arc is initially formed upon s'eparation of the bayonet or rod contact 94 from the tulip type contact 93.

The latter is arranged within a casting 95 which supports outer insulating shell 96 by means of supporting ring 97 and a set of screws 98. The arc extinguishing stack structure 91 is preferably made of oil absorbent fiber and compris'es a portion situated above the annular auxiliary lectrode 90 and designed for interruption 'of relatively high currents and a portion situated below the auxliary electrode 90 and designed for interruption of relatively low Currents. The upper portion of the stack structure 91 is arranged immediately adjacent the Stationary contact 93. The formation of a substantial pressure 'generating space between contact 24 and the upper portion of stack structure 91 as shown in Fgs. 3 and 4 is dispensed with in Fig. 5.

The upper portion of stack structure 91 is provided with a plurality of transverse venting passages 99 formed between contiguous plates of the staclt structure. Vent passages 99 'perrnt escape of products of arcing through one or more lateral or transversal passages 100, provided in shell 96. Preferably the venting passages 99 are angularly dsplaced 'to prevent miXing of the products of arcing exhausting theretrorn. A contact passageway '101'ex'tends along the entire arc extinguishing stack '91. Oil and gas retaining or trapping pockets 102 are forrned in the upp'er portion ot stck 91 at the side of passageway 101 remote from venting passages the deeornposition under heat by the are of oil trapped in 'pocliets 102 produces a strong arc extinguishir'g blast action in a direction transverse to that of contact separation. This action occurs provided that the current under interrupton is sufficiently high. If the requirenent of relativel'y high current intensity is met, the arc formed between contacts 93 and 94 Will be extinguished before the 'rod contact 94 has left the upper or high current interruptng portion of the arc extinguishing stack structure 91.

The annular electrode 90 has surfaces 103 of are ressting metal and is connected to a resistor 104 by means of transverse s'tnd 105 passing through transverse bore 106 in insulating shell 96. The end of resistor 104 rernote from stud '105 is conductively connected to ring 97 casting 95 and stationary contact 93.

Stampe out portions in contguous plates of the lower portion of stack structure 91 define transverse venting passages 107 of substantially smaller 'cross sectional area than the transverse venting passages 100 in the upper portion of the stack structure. Products of arcing escap- 99. Pressure gas resulting from ing from venting passages 107 are allowed to escape through lateral passage 108 provided in insulating shell 96.

The lower portion of 'shell 96 defines 'a relatively large oil filled pressure generating chamber 92 Situated at the end of the arc extinguishing stack structure 91 remote from stationary contact 93. Pressure generating chamber 92 is provided with an inner lining 109 and is closed at the bottom thereof by a cover plate 110 having a bore 111 for the passage of rod contact 94. 'Cover plate 110 as Well as insulating shell 96 are preferably rnade of a lamin'ted synthetic phenolic resin. The plates by which the lower portion of s'tack structure 91 is made up have stam'ped out 'portions which define an eccentric longitudinal passage 112 and transverse passages 113 adapted to be vented through the venting passages 107.

Low current a'rcs formed between the annular auxiliar'y electrode 99 and rod contact 94 generate an appreciable amount of gas When drawn into the pressure generating chamber 92. The only way of escape of the gases there generated is through pasages 112, 113, and 107, as indicated in Fi". 5 by a pl-u'rality of arrows. Since the area of escape of the gases generated in charnber 92 is relatively limited, the decay of pressure in chamber 92 is likewise limited and the velocity or" the escaping gases will be relatively high, resulting in an arc extinguishing action sufficently intense to rapidly extinguish any low current arc.

One of the advantages inherent in the embodiment of the invention shown in Fig. 5 consists in that high current arcs are subjected immediately upon their initiation to an intense 'extinguishing action, there being no delay resulting from drawing the arcs through a more or less Voluminous pressure generating chamber Situated between the point of arc initiation and the arc extinguishing stack structure. The pressure generating chamber is arranged in such a way that it becomes effective only when its operation is vital to that of the inter'rupting device, i. e., upon formation of a low current are in series with a current and voltage limitng resistor.

Figs. 6 and 7 illustrate a way of arranging two interrupting devices 60 of the type illustrated in Fig; 4 and their associated resistors 75 in a cylindrical tank 116. Interrupting devices 60 are arranged on opposite sides of a lift rod guiding structure 117. The lift rod guiding structure 117 supports at opposite ends thereof a pair of resistor supports 118. Each resistor support 1 18 supports a shunting resistor 75. Suitable leads 119 connect each shunting resistor 75 to its associated interrupting cevice 60. The resistors are of the linear type and are formed of wires wound around a pair of insulating tubular members 120 and 121. The tubular members 120 and 121 extend from plates 122 which form integral parts of resistor supports 118.

It will be observed that a common feature of all embodinents of the invention shown consists in providing highly efiective venting means in an arc extinguishing stack structure immediately adjacent the point of arc initiation and in minimizing venting in another arc extinguishing stack structure Situated most remotely from the point of arc initiation. in the ernbodirnent of the invention shown in Fig'. 3 the scaling means 39 in the nature of 'a gland surrounding the rod contact 27 at the exit end of the stack structure 33 limits venting of the lower stack structure 21 to the passages through the upper stack structure 20. Ii other' Words, the upper stack structure is praetically the only avenue of egress of fluid under pressure from the lower one, thereby resulting in the generation of relatively high pressures in the lower one by arcs of relatively small intensity in series with resistor 49.

In the embodiment of the invention shown in Fig'. 5 the lower part of the arc extin'guishing structure 91 has venting openings 107 of its own; but these venting openings are relatively small, 'resulting' a relatively slow pressure decay within chamber 92 and consequently forrnation of transverse arc extinguishing blasts of sufficiently high velocity and duration to ei'fect extinction of small intensity arcs.

Circuit breakers according to this invention are primariiy intended to broaden the range of application of Suicide type oil circuit brealrers. They are applicable where prior art circuit breal ers of the suicide type are not capabie any longer to cope with the severity of interrupticn, i. c., where, heretofore, circuit breakers comprising an auxiliary piston oil pump for extinguishing small current arcs by oil jet action had to he used. In other words, the Suicide type circuit breakers according to this invention are surTiciently effective to interrupt circuits that could not be interrupted heretofore by oil circuit breakers without resorting to auxiliary piston oil pumps.

lt will be seen from the foregoing that the circuit breakers according to this invention are multipurpose circuit breakers, i. e., they are adapted to cope equally well with large currents and small Currents. They are equally well adapted to interrupt small lagging currents and small leading Currents. As far as interruption of small Currents is concerned, these circuit breakers are particularly well adapted to cope with situations arising when the voltage gradient across the Contacts tends to exceed the dielectric strength between the contacts as in case of interruption of predominantly capacitive loads, for example, static condensers. The resistors in circuit breakers according to this invention maintain the circuit recovery voltages below the breakdown voltage of other apparatus associated with the circuit, thus constitutng an important safety feature not present in auxiliary piston purnp type oil circuit breakers. Furthermore, this invention lends itself to circuit breaker modernization, i. e., existing prior art circuit breakers may be rebuilt at moderate cost to withstand a higher recovery voltage without the need of changing the Operating mechanism to increase the speed of contact separation.

Although but a few emhodiments of the present invention have been illustrated and described it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

it is claimed and desired to secure by Letters Patent:

i. A circuit breaker comprising an arc extingushing iiquid, an arc extinguishing device submerged in said liquid and defining a substantially straight passageway through said device and a substantially helical passageway extending radially from said straight passageway and having an internal diameter equal to the diameter of said straight passageway, a pressure generating chamber arranged adjacent one end of said straight passageway and said helical passageway, relatively movable contact means comprising a first and second contact for initiating arcs within said chamber to produce a substantially helical flow of arc extinguishing liquid through said helical passageway, said second contact being arranged to be moved within said straight passageway and out of said arc extinguishing device, an auxiliary electrode means arranged within said arc extinguishing device between the ends thereof and positioned to be exposed to said substantially helical fiow of arc extnguishing liquid, and a resistor conductively connected at one end thereof to said first contact and at the other end thereof to said auxiliary electrode for aiding arc extinguishment.

2. A circuit breaker comprising an arc extinguishing liquid, and arc extinguishing device submerged in said liquid and defining a substantially straight passageway through said device and a substantially helical passageway surrounding said straight passageway and communicating therewith, a pressure generating chamber arranged adjacent one end of said straight passageway, relatively movable contact means comprising a first contact and a second contact arranged within said chamber for initiat-' ing arcs therein, said second contact being arranged to move within said straight passageway and out of said arc extinguishing device, an auxiliar electrode means arranged at one level only between the ends of said straight passageway and said helical passageway, and a resistor conductively connected at one end thereof to said first contact and at the other end thereof to said auxiliary electrode, said electrode means subdividing said straight passageway into a first portion wherein arcs formed between said first contact and said second contact in parallel with said resistor are quenched by the action of the portion of said helical passageway surrounding said first portion of said straight passageway and into a second portion wherein arcs formed between said auxiliary electrode means and said second contact in series with said resistor are quenched by tion of said helical passageway surrounding said second portion of said straight passageway.

3. A circuit breaker comprising a tank containing an arc extinguishing liquid, an arc extinguishing stack structure defining a substantially straight passageway and also defining a substantially helical passageway extending radially from said straight passageway, contact means for initating arcs and drawing said arcs into said straight passageway, said contact means comprising a fixed contact and a movable rod shapecl contact, said novable contact being circular in cross section and adapted to 'oe moved within said straight passageway and to be completely withdrawn thererom into said tank, a fixed auxiliary electrode arranged immediately adjacent the path of said contact rod in said straight passageway and between the ends of said straight passageway, a fixed resistor arranged outside of said S"-Cl structure connected with one end thereof to said auxiliary electrode and the other end to said fixed contact and adapted to Shunt arcs extending between the region of arc initiation and said contact rod, means dened by said stack structure for venting the portion of said strai ht passageway located between said region of arc initia'tion and the point of said stack structure where said auxiliary electrode is arranged; and means for rninirnizing venting of the portion of said straight passageway located between the point of said stack structure where said auxiliary electrode is arranged and the point of withdrawal from said stack structure of said contact rod, said venting minimizing means including a gland arranged immediately adjacent said point of withdrawal having an internal diameter only slightly in excess of the diameter of said contact rod to minimize the clearance therebetween.

4. A crcuit breaker comprising a vessei containing an arc extinguishing liquid, an arc extingnishing structure defining a substantially straight passageway and also defining a passageway extending radially from said straight passageway, a pressure charnber arranged adjacent one end of said straight p'assageway, contact means for initiating arcs and drawing said arcs into said straight passageway, said contact means including a fixed tulip type contact arranged within said chamher at the side thereof remote from said stack structure and a rod type contact adapted to be moved within said straight passageway and completely withdrawn th refren into said vessel, a resistor conductively connected at one end thereof to said tulip type contact, a stud conductively connected to the other end of said resistor and projecting transversely through said shell toward said straight passageway, an auxiliary electrode arranged to be exposed to a flow of liquid established within said straight passageway, said auXiliary electrode being in conductive contact with the radially inner end of said stud, means for venting the portion of said straight passageway adjacent said tulip type contact, and separate means for venting the portion of said straight passageway more renote from said tulip typ'e contact than said auxiliary electrode, said first mentioned venting means having a larger minimum cross sectional area than said separate venting means.

5. A circuit breaker comprising a tank containing an arc extinguishing liquid, an arc extinguishing stack structure mounted within said tank and submerged in said liquid, said stack structure being made up of superposed liquid absorbent plates having openings defining a substantially straight passageway and also defining a substantially helical passageway surrounding said straight passageway and communicating thercwith, a pressure resistant shell housing said stack structure, contact means for initating arcs and drawing said arcs into said straight passageway including a first contact arranged adjacent one end of said straight passageway and a second rod shaped contact adapted to be moved within said straight passageway and to be completely withdrawn from said stack structure into said tank, a fixed resistor conductively connected with one end thereof to said first contact, a conductive stud connected to the other end of said resistor and projecting transversely through said shell toward said straight passageway, an auxiliary electrode at least in part of annular configuration arranged to be cxposed to the whirling fiow of fluid established by the passage of fluid through said helical passageway, said auxiliary electrode being in conductive contact with the radially inner end of said stud and subdividing said straight passageway into a first portion Situated adjacent said first contact and a second portion Situated relati'vely remote from said first contact, 'means for venting said first portion and means in the nature of a gland surrounding said contact at the exit end thereoi from said stacl; structure to limit venting of said second portion except through said first portion.

6. A circuit breaker comprising a tank containing an arc extinguishing liquid, an arc extinguishing stack structure fixedly mounted within said tank and submerged in said liquid, said stack structure being formed of superposed plates having angularly displaced openings which define a substantially straight passageway and also define a plurality of substantially helical passageways surrounding said straight passageway and communicating therewith, a pressure resistant shet! housing said stack structure, contact means for initating arcs and drawing said arcs into said straight p'assageway including a first contact arranged adiacent one end of said straight passageway and a second rod shaped contact adapted to be moved within said straight passageway and to be completely withdrawn from said stack structure into said tank, a fixed resistor conductively connected With one end thereof to said first contact, a conductive stud connected to the other end of said resistor and projecting transversely through said shell toward said passageway, an auxiliary electrode arranged to be exposed to substantially helical flows of fluid established by the passage of fluid through said plurality of helical passageways, said auxiliary electrode being in conductive contact with the radially inner end of said stud and subdividing said straight passageway into a first portion situated adjacent said first contact and a second portion Situated relatively remote from said first contact, means for venting said 'first portion including a plurality of radial passagcways arranged in spaced relation along said first portion and scaling means at the exit end of said second contact from said stack structure to limit the escape of fluid from said second portion, said first portion and said sealing means being the only avenues of egress of fluid from said second portion.

7. A circuit breaker comprising a vessel containing an arc extin'guishing liquid, an arc extinguishing stack structure fixedly mounted within said vessel and submerged in said liquid, said stack structure being made up of superposed liquid absorbent piates having openings defining a substantially straight passageway and also defining liquid receiving recesses projecting radially from said passageway, a pressure resistant shell housing said stack structure and defining a pressure generating chamber Situated adjacent one end of said passageway, contact means comprising a fixed contact and a movable rod contact for initating arcs adjacent one end of said passageway and for drawing said arcs into said passageway, a fixed auxiliary electrode arranged within said passageway at a region remote from said chamber, and a resistor conductively connected to said fixed contact and said electrode, said electrode being arranged at a point located between the ends of said stack structure and suiciently close to said rod contact to cause formation of arcs across the gap formed between said electrode and said rod contact as said rod contact is withdrawn through said passageway.

8. A circuit breaker comprising a vessel containing an arc extinguishing liquid, first and second coaxially arranged arc extinguishing devices immersed in said liquid and defining a contact passageway extending through said devices, a fixed contact, a cooperating contact movable in said passageway for drawing arcs into said passageway, means defining a pressure generating chamber arranged adjacent one end of said passageway for producng an arc extinguishing flow of liquid by arc generated pressure through said devices, auxiliary electrode means arranged between the adjacent ends of said devices, and a resistor conductively connected between said fixed contact and said auxiliary electrode whereby an arc drawn between said contacts in said first device is shunted by said resistor as said movable contact moves through said first device and an arc 'drawn between said electrode and said second contact in said second device is in series with said resistor as said movable 'contact moves through said second device.

9. A circuit breaker comprising an arc extinguishing liquid, two coaxially arranged arc extinguishing devices submerged in said liquid and defining a substantially straight passageway through said devices and a substantially helical passageway extending radially from said straight passageway and having an internal diameter equal to the diameter of said straight passageway, means defining a pressure generating chamber arranged adjacent one end of said straight passageway and said helical passageway, a fixed contact disposed adiacent said pressure generating chamber, a cooperating movable contact for initating arcs within said pressure generating chamber to produce a substantially helical flow of arc extinguishing liquid through said helical passageway, said movable contact being arranged to be moved within said straight passageway and out of said arc extinguishing devices, an auxiliary electrode means arranged between the adjacent ends 'of said arc extinguishing devices and positioned to be 'exposed to said substantially helical fiow of arc extinguishng liquid, and a resistor conductively connected between 'said fixed contact and said auxiliary electrode for aiding arc extnguishment.

10. A circuit breaker 'comprising a vessel containing an arc extinguishing liquid, an arc extinguishing stack structure mounted within said vessel and submerged in said liquid, said stack structure comprising a plurality of superposed piates each having an opening comprising a central portion and at least one lateral, angularly displaced portion, said central portions of said plates being arranged in registry to define a straight passageway and at least one of said lateral, angularly displace'd portions in each said plate being arranged to define a substantially helcal passageway surrounding said straight passageway and communicating therewith, a pressure chamber arranged adjacent one end of said straight passageway, contact means for initating arcs within said chamber comprising a fixed contact mounted within said chamber and a movable contact actuated to pass through said chamber, said straight passageway and into said vessel, an auxiliary electrode means at least in part of annular configurati'on arranged between the ends of said straight passageway, and a resistor having one end thereof connected to said fixed contact and the other end thereof connected to said auxiliary electrode means, said auxiliary electrode means being arranged less than three quarters of the length of said straight passageway away from the arc initiation end of said straight passageway in a position so as to be exposed to the whirlng flow of liquid produced in the portion of said helical passageway Situated between said chamber and said auxiiary electrode means.

References Cited in the file of this patent UNITED STATES PATENTS Wyman Dec. 22, 1942 iu 14 Taylor Apr. 19, 1949 Matthews Apr. 1, 1952 FOREIGN PATENTS Great Britain Apr. 12, 1949 France June 21, 1922 

